07-Sep-2013 09:38, H. S. Teoh пишет:
On Sat, Sep 07, 2013 at 12:38:58AM -0400, Jonathan M Davis wrote:
On Friday, September 06, 2013 21:15:44 Timothee Cour wrote:
I'd like to have a function:
@nothrow bool isNumberLitteral(string a);
unittest{
assert(isNumberLitteral("1.2"));
assert(!isNumberLitteral("a1.2"));
assert(!isNumberLitteral("a.b"));
}
I want it nothrow for efficiency (I'm using it intensively), and
try/catch as below has significant runtime overhead (esp when the
exception is caught):
You could try std.string.isNumeric.
But it's true that it would be nice to have some sort of counterpart
to std.conv.to which checked whether a conversion was possible or
which returned its argument via an out parameter and returned whether
it succeeded or not (or something similar) for cases where you need to
avoid throwing.
http://d.puremagic.com/issues/show_bug.cgi?id=6840
http://d.puremagic.com/issues/show_bug.cgi?id=6843
[...]
I like the idea of maybeTo!(). But I'm not sure if it's possible to
guarantee performance -- conversion to user-defined types, for example,
may involving a ctor that might throw. If so, it's impossible to
implement maybeTo!() without using try/catch, so the performance hit
will still be there.
As it's a template it could be inferred as nothrow for basic types.
I've been constantly looking for something like:
bool tryTo(T)(ref T dest, ...<same args as in to>)
That either parses successfully or returns false and leaves dest unaffected.
But at least, it will buy us performance when basic types are used.
T
--
Dmitry Olshansky
